/* BEValue - Holds different types that a bencoded byte array can represent.
   Copyright (C) 2003 Mark J. Wielaard

   This file is part of Snark.
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   
   In addition, as a special exception, the copyright holders of Snark give
   you permission to combine Snark with free software programs or libraries
   that are released under the GNU LGPL and with any code released under
   the Apache Software License, version 1.0, 1.1 or 2.0. You may copy and
   distribute such a system following the terms of the GNU GPL for Snark
   and the following licenses of the other code concerned, provided that
   you include the source code of that other code when and as the GNU GPL
   requires distribution of source code.

   Note that people who make modified versions of Snark are not
   obligated to grant this special exception for their modified versions;
   it is their choice whether to do so. The GNU General Public License
   gives permission to release a modified version without this exception;
   this exception also makes it possible to release a modified version
   which carries forward this exception.
*/

package org.klomp.snark.bencode;

import java.io.UnsupportedEncodingException;
import java.util.List;
import java.util.Map;

/**
 * Holds different types that a bencoded byte array can represent.
 * You need to call the correct get method to get the correct java
 * type object. If the BEValue wasn't actually of the requested type
 * you will get a InvalidBEncodingException.
 *
 * @author Mark Wielaard (mark@klomp.org)
 */
public class BEValue
{
  // This is either a byte[], Number, List or Map.
  private final Object value;

  public BEValue(byte[] value)
  {
    this.value = value;
  }

  public BEValue(Number value)
  {
    this.value = value;
  }

  public BEValue(List value)
  {
    this.value = value;
  }

  public BEValue(Map value)
  {
    this.value = value;
  }

  /**
   * Returns this BEValue as a String. This operation only succeeds
   * when the BEValue is a byte[], otherwise it will throw a
   * InvalidBEncodingException. The byte[] will be interpreted as
   * UTF-8 encoded characters.
   */
  public String getString() throws InvalidBEncodingException
  {
    try
      {
	return new String(getBytes(), "UTF-8");
      }
    catch (ClassCastException cce)
      {
	throw new InvalidBEncodingException(cce.toString());
      }
    catch (UnsupportedEncodingException uee)
      {
	throw new InternalError(uee.toString());
      }
  }

  /**
   * Returns this BEValue as a byte[]. This operation only succeeds
   * when the BEValue is actually a byte[], otherwise it will throw a
   * InvalidBEncodingException.
   */
  public byte[] getBytes() throws InvalidBEncodingException
  {
    try
      {
	return (byte[])value;
      }
    catch (ClassCastException cce)
      {
	throw new InvalidBEncodingException(cce.toString());
      }
  }

  /**
   * Returns this BEValue as a Number. This operation only succeeds
   * when the BEValue is actually a Number, otherwise it will throw a
   * InvalidBEncodingException.
   */
  public Number getNumber() throws InvalidBEncodingException
  {
    try
      {
	return (Number)value;
      }
    catch (ClassCastException cce)
      {
	throw new InvalidBEncodingException(cce.toString());
      }
  }

  /**
   * Returns this BEValue as int. This operation only succeeds when
   * the BEValue is actually a Number, otherwise it will throw a
   * InvalidBEncodingException. The returned int is the result of
   * <code>Number.intValue()</code>.
   */
  public int getInt() throws InvalidBEncodingException
  {
    return getNumber().intValue();
  }

  /**
   * Returns this BEValue as long. This operation only succeeds when
   * the BEValue is actually a Number, otherwise it will throw a
   * InvalidBEncodingException. The returned long is the result of
   * <code>Number.longValue()</code>.
   */
  public long getLong() throws InvalidBEncodingException
  {
    return getNumber().longValue();
  }

  /**
   * Returns this BEValue as a List of BEValues. This operation only
   * succeeds when the BEValue is actually a List, otherwise it will
   * throw a InvalidBEncodingException.
   */
  public List getList() throws InvalidBEncodingException
  {
    try
      {
	return (List)value;
      }
    catch (ClassCastException cce)
      {
	throw new InvalidBEncodingException(cce.toString());
      }
  }

  /**
   * Returns this BEValue as a Map of BEValue keys and BEValue
   * values. This operation only succeeds when the BEValue is actually
   * a Map, otherwise it will throw a InvalidBEncodingException.
   */
  public Map getMap() throws InvalidBEncodingException
  {
    try
      {
	return (Map)value;
      }
    catch (ClassCastException cce)
      {
	throw new InvalidBEncodingException(cce.toString());
      }
  }

  public String toString()
  {
    String valueString;
    if (value instanceof byte[])
      {
	byte[] bs = (byte[])value;
	// XXX - Stupid heuristic...
	if (bs.length <= 12)
	  valueString = new String(bs);
	else
	  valueString = "bytes:" + bs.length;
      }
    else
      valueString = value.toString();

    return "BEValue[" + valueString + "]";
  }
}
